Three-year clinical and angiographic follow-up after intracoronary radiation : results of a randomized clinical trial

Long-term clinical outcomes of intravascular brachytherapy for multilayer drug-eluting in-stent restenosis

BACKGROUND

Multilayer in-stent restenosis (ISR) remains a clinical challenge. Intravascular brachytherapy (IVBT) offers a "metal-free" treatment modality for multilayer drug-eluting stent (DES)-ISR; however, long-term outcome data on IVBT safety and efficacy are lacking.

AIMS

We sought to compare 3-year clinical outcomes between patients treated with IVBT and those treated with a non-IVBT strategy.

METHODS

Patients treated for multilayer DES-ISR (≥2 layers) at Mount Sinai Hospital (2012-2019) were included for analysis. The primary outcome was major adverse cardiac events (MACE), a composite of all-cause death, target lesion revascularisation and myocardial infarction, at 3-year follow-up.

RESULTS

A total of 647 patients (mean age 66.6±9.9 years, 25.5% female) were included: 453 patients (70%) were treated with IVBT and 194 patients (30%) with a non-IVBT strategy. Baseline characteristics were similar, except for IVBT-treated patients having a higher incidence of prior coronary artery bypass grafting. The IVBT group had a lower mean SYNTAX score (11.9±10.7 vs 14.2±11.3; p=0.028) and were significantly less likely to receive a DES (0.4% vs 25.8%; p<0.001). At 3-year follow-up, the incidence of MACE was lower in the IVBT-treated group compared to the non-IVBT group (propensity score-adjusted analysis: 39.5% vs 47.8%; hazard ratio 0.73, 95% confidence interval: 0.53-0.99; p=0.044). There were no significant differences between the incidence of the individual components of MACE in each group.

CONCLUSIONS

Multilayer DES-ISR is associated with a high rate of adverse outcomes at 3-year follow-up. Treatment with IVBT was associated with a lower rate of MACE compared to treatment with a non-IVBT strategy at long-term follow-up.

Improved safety and quality in intravascular brachytherapy: A multi-institutional study using failure modes and effects analysis

PURPOSE

Highlight safety considerations in intravascular brachytherapy (IVBT) programs, provide relevant quality assurance (QA) and safety measures, and establish their effectiveness.

METHODS AND MATERIALS

Radiation oncologists, medical physicists, and cardiologists from three institutions performed a failure modes and effects analysis (FMEA) on the radiation delivery portion of IVBT. We identified 40 failure modes and rated the severity, occurrence, and detectability before and after consideration of safety practices. Risk priority numbers (RPN) and relative risk rankings were determined, and a sample QA safety checklist was developed.

RESULTS

We developed a process map based on multi-institutional consensus. Highest-RPN failure modes were due to incorrect source train length, incorrect vessel diameter, and missing prior radiation history. Based on these, we proposed QA and safety measures: ten of which were not previously recommended. These measures improved occurrence and detectability: reducing the average RPN from 116 to 58 and median from 84 to 40. Importantly, the average RPN of the top 10% of failure modes reduced from 311 to 172. With QA considered, the highest risk failure modes were from contamination and incorrect source train length.

CONCLUSIONS

We identified several high-risk failure modes in IVBT procedures and practical safety and QA measures to address them.

The birth, decline, and contemporary re-emergence of endovascular brachytherapy for prevention of in-stent restenosis

Despite the advent of drug-eluting stents and dual antiplatelet therapy in the interventional management of cardiovascular disease, restenosis rates remain high with significant sequelae. Endovascular brachytherapy-popular in the 1990s and early 2000s-has recently resurfaced as a cost-effective treatment option. In this work, we outline the history of endovascular brachytherapy starting with its earliest promise in the 1990s. We discuss the development of drug-eluting stents and dual antiplatelet strategies and their impact on the perceived benefit of endovascular brachytherapy. For the contemporary era, we propose novel roles for endovascular brachytherapy in complex coronary artery disease and in high-risk patients managed with drug-eluting stents. We discuss the impetus for reducing the requirement and duration of dual antiplatelet therapy using endovascular brachytherapy. We also review innovative opportunities for endovascular brachytherapy after bare-metal stent placement in both coronary and noncoronary territories and offer economic arguments in favor of endovascular brachytherapy. Trials of endovascular brachytherapy in these regimes are merited.

Management of ischemic coronary disease in patients receiving chemotherapy: an uncharted clinical challenge

Acute coronary syndrome (ACS) coinciding with active malignancy presents a unique clinical challenge given intersecting pathophysiology and treatment-related effects. There is little established clinical guidance on management strategies, rendering most treatment approaches anecdotal. We present a case highlighting the complexity of managing a patient being treated for malignancy who concurrently suffers from ACS. We then review the literature on co-management of ACS and malignancy, including reports of specific cancer therapies associated with ACS, unique features of clinical presentation and optimal use of dual antiplatelet therapy to minimize risks of bleeding and thrombosis. We also describe gaps in current literature, challenges in systematically studying the clinical intersection of these disease processes and propose alternative methodologies for further research.

Utilizing the Foreign Body Response to Grow Tissue Engineered Blood Vessels in Vivo

It is well known that the number of patients requiring a vascular grafts for use as vessel replacement in cardiovascular diseases, or as vascular access site for hemodialysis is ever increasing. The development of tissue engineered blood vessels (TEBV's) is a promising method to meet this increasing demand vascular grafts, without having to rely on poorly performing synthetic options such as polytetrafluoroethylene (PTFE) or Dacron. The generation of in vivo TEBV's involves utilizing the host reaction to an implanted biomaterial for the generation of completely autologous tissues. Essentially this approach to the development of TEBV's makes use of the foreign body response to biomaterials for the construction of the entire vascular replacement tissue within the patient's own body. In this review we will discuss the method of developing in vivo TEBV's, and debate the approaches of several research groups that have implemented this method.

Intravascular brachytherapy for peripheral vascular disease

BACKGROUND

Interventional treatment of arteries that are narrowed and obstructed by atherosclerosis involves either bypassing the blockage using a graft; widening the artery from the inside with a balloon, a procedure known as percutaneous transluminal angioplasty (PTA); or providing a strut to hold the vessel open, known as a stent. All of these treatments are, however, limited by the high numbers that fail within a year. Intravascular brachytherapy is the application of radiation directly to the site of vessel narrowing. It is known to inhibit the processes that lead to restenosis (narrowing) of vessels and grafts after treatment. This is an update of a review first published in 2002.

OBJECTIVES

To assess the efficacy of, and complications associated with, intravascular brachytherapy (IVBT) for maintaining patency after angioplasty or stent insertion in native vessels or bypass grafts of the iliac or infrainguinal arteries.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched their Specialised Register (last searched August 2013) and CENTRAL (2013, Issue 7).

SELECTION CRITERIA

Randomised controlled trials of the use of brachytherapy as an adjunct to the endovascular treatment of people with peripheral arterial disease (PAD) or stenosed bypass grafts of the iliac or infrainguinal arteries versus the procedure without brachytherapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and two other review authors independently extracted the data. Adverse event information was collected from the trials.

MAIN RESULTS

Eight trials with a combined total of 1090 participants were included in this review. All included studies used the femoropopliteal artery. We did not identify any studies that used the iliac arteries. All studies compared PTA with or without stenting plus IVBT versus PTA with or without stenting alone. No trials were found comparing IVBT to technologies such as drug eluting stents or balloons, or cryoplasty. Follow-up ranged from six months to five years. The quality of the included trials was moderate with our concerns relating to the difficulty of blinding due to the nature of the procedures and the small sample sizes for some studies. Primary outcomes (patency or restenosis and need for re-intervention) were reported in the majority of the trials, but reporting at various time points and the use of multiple definitions of the outcomes by the included studies meant that not all data were available for pooling. The secondary outcomes were not reported in many of the included studies.For brachytherapy, cumulative patency was higher at 24 months (odds ratio (OR) 2.36, 95% confidence interval (CI) 1.36 to 4.10, n = 222, P = 0.002). A statistically significant difference was found for restenosis at six months (OR 0.27, 95% CI 0.11 to 0.66, n = 562, P = 0.004), 12 months (OR 0.44, 95% CI 0.28 to 0.68, n = 375, P = 0.0002) and 24 months (OR 0.41, 95% CI 0.21 to 0.78, n = 164, P = 0.007) in favour of IVBT. No difference was found after five years as measured in one study. The need for re-interventions was reported in six studies. Target lesion revascularisation was significantly reduced in trial participants treated with IVBT compared with angioplasty alone (OR 0.51, 95% CI 0.27 to 0.97, P = 0.04) at six months after the interventions. No statistically significant difference was found between the procedures on the need for re-intervention at 12 and 24 months after the procedures.A statistically significant lower number of occlusions was found in the control group at more than three months (OR 11.46, 95% CI 1.44 to 90.96, n = 363, P = 0.02) but no differences were found at less than one month nor at 12 months after the procedures making the clinical significance uncertain. Ankle brachial index was statistically significantly better for IVBT at the 12 month follow-up (mean difference 0.08, 95% CI 0.02 to 0.14, n = 100, P = 0.02) but no statistically significant differences were found at 24 hours and at six months.Quality of life, complications, limb loss, cardiovascular deaths, death from all causes, pain free walking distance and maximum walking distance on a treadmill were similar for the two arms of the trials with no statistically significant difference found between the treatment groups.

AUTHORS' CONCLUSIONS

The evidence for using peripheral artery brachytherapy as an adjunct to percutaneous transluminal angioplasty to maintain patency and for the prevention of restenosis in people with peripheral vascular disease is limited, mainly due to the inconsistency of assessment and reporting of clinically relevant outcomes. More data are needed on clinically relevant outcomes such as health related quality of life (HRQOL) or limb salvage and longer-term outcomes, together with comparisons with other techniques such as drug eluting balloons and stents. Adequately powered randomised controlled trials, health economics and cost-effectiveness data are required before the procedure could be recommended for widespread use.

Role of biomaterials in prevention of in-stent restenosis

Coronary balloon angioplasty and coronary stenting are the procedures used in healing coronary artery disease. However, injury of arteries during angioplasty and stenting causes cell stimulations in tissue. Cell movement and thrombosis lead to re-narrowing of widened vessel called restenosis. Several new types of carriers and technology have been developed to suppress and/or prevent restenosis. Authors review the polymeric materials featured in drug/gene carrier systems, nanovehicles, and stent coating materials against restenosis.

Long-term serial angiographic outcomes after sirolimus-eluting stent implantation

OBJECTIVE

We evaluated, using quantitative coronary angiography, the natural history of change that occurred in target lesions after successful sirolimus-eluting stent (SES) implantation.

BACKGROUND

Percutaneous coronary intervention with drug-eluting stents (DES) has significantly reduced the rate of repeated target lesion revascularization. However, early studies have raised concerns regarding the "late catch-up" phenomenon of DES.

METHODS

Between June 2004 and March 2007, consecutive 217 patients with 306 lesions without restenosis at early angiographic follow-up underwent late angiographic follow-up (early follow-up: 11.2 ± 2.1 months and late follow-up: 29.4 ± 5.2 months). Predictors of late catch-up were identified with univariate and multivariate regression analyses.

RESULTS

Although reference vessel diameter did not significantly change during follow-up [3.15 mm (interquartile range (IQR): 2.81-3.49 mm), 3.12 mm (IQR: 2.79-3.47 mm), and 3.08 mm (IQR: 2.76-3.46 mm) at postprocedure, and early and late angiographic follow-up, respectively; P = 0.2653], late loss (LL) significantly increased during follow-up [0.05 mm (IQR: 0.00-0.13 mm) and 0.08 mm (IQR: 0.01-0.19 mm) at early and late follow-up, respectively; P < 0.0001]. Univariate analysis showed previous intervention, adjunctive use of cutting balloon, lesion length, and progression of MLD, LL, %DS at early follow-up as predictors of late catch-up. Multivariate regression analysis identified %DS at early follow-up as a predictor of late catch-up (OR 1.076, CI 1.039-1.114, P < 0.0001).

CONCLUSION

Significant and continuous progression of neointima after SES implantation was observed in the present study. Larger LL may be a sign of late catch-up phenomenon.

Five-year follow-up of the Sirolimus-Eluting Stents vs Vascular Brachytherapy for Bare Metal In-Stent Restenosis (SISR) trial

OBJECTIVES

The aim of this study was to evaluate the 5-year clinical safety and efficacy outcomes of patients treated for in-stent restenosis of bare-metal stents (BMSs).

BACKGROUND

The SISR trial is a prospective, randomized trial that compared the safety and efficacy of sirolimus-eluting stent (SES) vs vascular brachytherapy (VBT) for the treatment of BMS in-stent restenosis.

METHODS

A total of 384 patients with BMS in-stent restenosis were randomized to treatment with SES (n = 259) or VBT (n = 125) and were followed for 5 years.

RESULTS

At 5 years, the rates of target lesion revascularization (TLR) had narrowed and were nonsignificant between the SES and VBT groups, with TLR rates of 24.7% and 31.2% (95% CI -16.3% to 2.8%, P = .179) respectively. Target vessel failure was 33.6% vs 36.8% (95% CI -13.5% to 6.7% P = .568) for SES compared with VBT. The rate of major adverse cardiac event at 5 years was 34.0% vs 36.8% (95% CI -13.1% to7.1%, P = .648) for the SES compared with VBT. There were no differences between SES and VBT in terms of survival free from TLR (72.9% vs 66.4%, log-rank P = .08) or from target vessel failure (64.4% vs 61.3%, log-rank P = .349). There were no significant differences in the rates of definite/probable stent thrombosis (5.9% vs 2.5%, 95% CI -7.9% to 1.3%, P = .182) between the 2 groups.

CONCLUSIONS

At a 5-year follow-up, no differences in safety or efficacy outcomes were observed for treatment of BMS restenosis with SES vs VBT. There were no significant differences in survival free from TLR, target vessel revascularization, or major adverse cardiac events between the 2 groups at 5 years. Sirolimus-eluting stent is a viable treatment option compared with VBT for BMS restenosis.

Radiation therapy for dialysis access stenosis: unfulfilled promise or false expectations

Hemodialysis vascular access dysfunction is a major cause of morbidity and hospitalization in the hemodialysis population at a cost of well over $1 billion per annum. Venous stenosis (due to venous neointimal hyperplasia [VNH]) is the most common cause of polytetrafluroethylene PTFE) dialysis access graft and arteriovenous fistula (AVF) failure. Despite the magnitude of the clinical problem, however, there are currently no effective therapies for this condition. We and others have previously demonstrated that VNH in PTFE dialysis grafts and AVF is composed of smooth muscle cells/myofibroblasts, endothelial cells within neointimal microvessels, and peri-graft macrophages. Radiation therapy blocks the proliferation and activation of all these cell types. The current review will dissect out the available in vitro, experimental, and clinical data on the use of radiation therapy for vascular stenosis in general, and for dialysis access dysfunction in particular. It is important to try and identify whether there is still a role for radiation therapy in this specific clinical setting. We believe that this is a critically important question to answer in view of the huge unmet clinical need that is currently associated with hemodialysis vascular access dysfunction.

Eight-year clinical outcome after radioactive stent implantation: a treatment failure without irreversible long-term clinical sequelae

AIMS

To assess the long-term outcome of patients who underwent radioactive stent (RS) implantation.

METHODS AND RESULTS

The RS study population consisted of 133 consecutive patients who underwent RS implantation between November 1997 and July 2000. They were matched using the propensity score method with 266 patients who underwent bare metal stenting (BMS) in the same span. Long-term survival status and information on MACE (death, non-fatal myocardial infarction or any re-intervention) was retrospectively obtained. Eight-year cumulative survival (90.2% vs. 87.4%, p = 0.57) was similar between the RS and BMS group respectively, while 8-year cumulative MACE-free survival was significantly lower in RS patients (42.1% vs. 64.3%, p < 0.001) due to the difference in events (mainly target lesion revascularisations [TLRs]) during the first year of follow-up (cumulative 1-year MACE-free survival: 59.4% vs. 86.7%, p < 0.001); there was no difference in the MACE rate after the first year (p = 0.71). The TLR rate at six months in the RS group was 29.3%, mainly due to edge restenosis and at one year 36.2% (control group: 9.5%, p < 0.001).

CONCLUSIONS

A high incidence of MACE and re-intervention was observed during the first year following RS implantation, mainly related to TLR for edge restenosis. After the first year, the clinical outcome of RS patients was similar to the control group indicating that there are no late adverse effects related to low dose-rate intracoronary radiation therapy.

3-year follow-up of the SISR (Sirolimus-Eluting Stents Versus Vascular Brachytherapy for In-Stent Restenosis) trial

OBJECTIVES

The aim of this study was to evaluate long-term outcome of patients treated for in-stent restenosis of bare-metal stents (BMS).

BACKGROUND

Treatment of restenosis of BMS is characterized by high recurrence rates. Vascular brachytherapy (VBT) improved outcome although late catch-up events were documented. Drug-eluting stents tested against VBT in this setting were found superior for at least the first year; superiority at longer follow-up is uncertain.

METHODS

We evaluated 3-year outcome of the multicenter SISR (Sirolimus-Eluting Stents Versus Vascular Brachytherapy for In-Stent Restenosis) trial, which randomized patients with restenosis of BMS to either a sirolimus-eluting stents (SES) or VBT.

RESULTS

Target vessel failure (cardiac death, infarction, or target vessel revascularization [TVR]) at 9 months as previously reported was significantly improved with SES. Kaplan-Meier analysis at 3 years documented that survival free from target lesion revascularization (TLR) and TVR continues to be significantly improved with SES: freedom from TLR 81.0% versus 71.6% (log-rank p = 0.018), and TVR 78.2% versus 68.8% (log-rank p = 0.022), SES versus VBT. At 3 years, target vessel failure and major adverse cardiac events (death, infarction, emergency coronary artery bypass grafting, or repeat TLR) remained improved with SES, but did not reach statistical significance. There was no statistically significant difference in definite or probable stent thrombosis (3.5% for SES, 2.4% for VBT; p = 0.758).

CONCLUSIONS

At 3 years of follow-up, after treatment of in-stent restenosis of BMS, patients treated with SES have improved survival free of TLR and TVR compared with patients treated with VBT. Stent thrombosis rates are not different between the 2 groups but are higher than reported in trials of treatment of de novo lesions.

Relationship of shear stress with in-stent restenosis: bare metal stenting and the effect of brachytherapy

BACKGROUND

The association of shear stress (SS) with in-stent restenosis after bare metal stenting is not clear. We investigated the significance of SS on predicting areas with neointima thickness (NT) in humans and the effect of vascular brachytherapy (VBT) following coronary artery stenting on the relationship of SS with NT.

METHODS

By using coronary angiography and intravascular ultrasound, we performed three-dimensional (3D) artery and stent reconstruction in 14 patients at 8-month follow-up after bare metal stenting with (stent&VBT group; 7 patients) or without (stent group; 7 patients) adjunctive beta-VBT. In-stent SS was calculated by applying computational fluid dynamics to the stent reconstruction and NT was determined in 3D space.

RESULTS

NT was significantly increased in the stent group (0.2+/-0.16 mm vs. 0.07+/-0.18 mm, p<0.001). The estimated intercepts and slopes regarding the relationship of NT with SS were 0.28 mm [95% confidence interval (CI): 0.20 to 0.36 mm, p<0.001] and -0.057 mm/Pa (95% CI: -0.062 to -0.052 mm/Pa, p<0.001) respectively for the stent group, and 0.15 mm (95% CI: -0.02 to 0.31 mm, p=0.082) and -0.017 mm/Pa (95% CI: -0.023 to -0.010 mm/Pa, p<0.001) respectively for the stent&VBT group. After pooling all data together, a significant effect of VBT on the relationship between NT and SS was found [estimate of interaction term (groupxSS) for stent&VBT vs. stent group: 0.04 mm/Pa; 95% CI: 0.032 to 0.049 mm/Pa, p<0.001].

CONCLUSIONS

In-stent restenosis is inversely related to SS after coronary artery stenting and VBT diminishes the inverse relationship between NT and SS.

Outcome differences with the use of drug-eluting stents for the treatment of in-stent restenosis of bare-metal stents versus drug-eluting stents

Drug-eluting stent (DES) implantation is the standard treatment for patients with bare-metal stent (BMS) in-stent restenosis (ISR) and is associated with low rates of target-vessel revascularization. Outcomes in patients with DES ISR treated using repeated DES placement are less certain. A total of 119 patients who presented with BMS ISR and 119 patients with DES ISR matched for baseline characteristics were evaluated. Both groups of patients were treated using DESs and compared with regard to major adverse cardiac events, including death, myocardial infarction, and target-vessel revascularization, at 1 year. Baseline characteristics were similar between groups. Compared with patients with BMS ISR, those with DES ISR had similar 1-year rates of death (5.1% BMS ISR vs 3.5% DES ISR; p = 0.75) and myocardial infarction (2.6% BMS ISR vs 3.5% DES ISR; p = 0.72) when treated using DESs. However, at 1 year, patients with DES ISR experienced significantly higher rates of target-vessel revascularization (10.3% BMS ISR vs 22.2% DES ISR; p = 0.01), with a trend toward increased overall major adverse cardiac events, including death, myocardial infarction, and target-vessel revascularization (16.0% BMS ISR vs 25.2% DES ISR; p = 0.08). Stent thrombosis occurred with similar frequency in both groups (2.5% BMS ISR vs 0.8% DES ISR; p = 0.62). In conclusion, DES ISR continues to be a therapeutic challenge because patients with DES ISR treated using DESs experience higher rates of recurrence compared with patients with BMS ISR treated using DESs. The optimal treatment of patients with DES restenosis remains to be defined.

Irradiation and dosimetry of Nitinol stent for renal artery brachytherapy

This study was conducted to assess the suitability of (48)V radioactive stent for use in renal artery brachytherapy. A nickel-titanium alloy Nitinol stent was irradiated over the proton energy range of up to 8.5 MeV, to obtain (48)V. The depth dose distribution analysis of the activated stent was done with TLD-700 GR in a Perspex phantom. We investigated a unique mixed gamma/beta brachytherapy source of (48)V. For a 10mm outer-diameter (48)V stent, the average measured dose rate to vessel was 37 mGy/h. The dosimetry results of the (48)V stent suggest that the stent is suitable for use in renal artery brachytherapy.

Approaches for prevention of restenosis

Coronary artery disease is characterized by a narrowing (stenosis) of the arteries that supply blood to the tissue of the heart. Continued restriction of blood flow manifests itself as angina and ultimately myocardial infarction (heart attack) for the patient. Heart bypass was once the only treatment for this condition, but over the years percutaneous coronary intervention (PCI) has become an increasingly attractive alternative to medical therapy and surgical revascularization for the treatment of coronary artery disease. A vascular stent is a medical device designed to serve as a temporary or permanent internal scaffold, to maintain or increase the lumen of a blood vessel. Metallic coronary stents were first introduced to prevent arterial dissections and to eliminate vessel recoil and intimal hyperplasia associated with PCI. Further advancement in the treatment of coronary artery disease is the development of drug-eluting stents that dramatically reduce the incidence of in-stent restenosis to less than 5%. Local drug delivery offers the advantages of allowing a relatively high local concentration of drug at the treatment site while minimizing systemic toxic effect. This review describes approaches for prevention of restenosis. It focuses on drugs for prevention of restenosis, bare metal stents, and drug-eluting stents. It also describes recent advances in bioresorbable stents. One of the chapters is dedicated to our novel composite bioresorbable drug-eluting fibers, designed to be used as basic elements in drug-eluting stents.

A meta-analysis of randomised controlled trials assessing drug-eluting stents and vascular brachytherapy in the treatment of coronary artery in-stent restenosis

OBJECTIVE

We undertook a meta-analysis of randomised trials assessing the outcome of vascular brachytherapy (VBT) or DES for the treatment of coronary artery ISR.

METHODS AND RESULTS

Studies utilising DES or VBT for ISR were identified by a systematic search. Data was pooled and combined overall effect measures were calculated for a random effect model in terms of deaths, myocardial infarctions, revascularisation, binary restenosis, mean late luminal loss and major adverse cardiac events (MACE). Fourteen eligible studies (3103 patients) were included. Neither therapy had any effect on mortality or myocardial infarction rate. VBT reduced the rate of revascularisation (RR 0.59, 95%CI 0.50-0.68), MACE (RR 0.58, 95%CI 0.51-0.67), binary restenosis (RR 0.51, 95%CI 0.44-0.59) and late loss (-0.73 mm, 95%CI -0.91 to -0.55 mm) compared to balloon angioplasty and selective bare metal stents (BMS) alone at intermediate follow-up and MACE (RR 0.72, 95%CI 0.61-0.85) at long-term follow-up. DES reduced the rate of revascularisation (OR 0.51, 95% CI 0.36-0.71), MACE (OR 0.55, 95% CI 0.39-0.79) and binary restenosis (OR 0.57, 95% CI 0.40-0.81) compared to VBT but follow-up was limited to 9 months.

CONCLUSIONS

VBT improves the long-term outcome of angioplasty compared with BMS alone in the treatment of ISR. DES appears to provide similar results to that of VBT during short-term follow-up.

Utility of drug-eluting stents in complex lesions and high-risk patients

Drug-eluting stents represent a breakthrough technology designed to deliver high concentrations of a bioactive agent locally to an atherosclerotic lesion, thereby minimizing systemic side effects of the drug. The safety and efficacy of drug-eluting stents have clearly been demonstrated in noncomplex lesions. This article presents an evidence-based analysis of the current experience with CYPHER sirolimus-eluting stents (Cordis Corp., Miami Lakes, FL) and TAXUS paclitaxel-eluting stents (Boston Scientific, Natick, MA) in a broad spectrum of high-risk and/or complex subsets of patients and lesions, including those with diabetes mellitus, multivessel disease, diffuse disease, very small vessels, lesions in saphenous vein grafts, chronic total occlusions, in-stent restenosis, ostial and bifurcation lesions, unprotected left main disease, and acute myocardial infarction. Emerging data in several of these subsets suggest that drug-eluting stents are safe and effective, and their use may currently be recommended, whereas in other groups of patients and lesions the efficacy and/or safety of drug-eluting stents remains to be determined, thus warranting caution. It is anticipated that penetration of drug-eluting stents will continue to increase, and fewer patients will require surgical revascularization to achieve sustained event-free survival.

Use of sirolimus-eluting stents for treatment of in-stent restenosis: long-term follow-up

OBJECTIVES

The aims of this study were to assess (i) the feasibility, safety and efficacy of sirolimus-eluting stents (SESs) in treating in-stent restenosis (ISR), (ii) the risk factors for recurrent ISR, and (iii) the long-term major adverse cardiac events (MACE).

METHODS

Between May 2002 and April 2004, 100 consecutive patients with evidence of myocardial ischaemia and 112 ISRs in native coronary arteries were treated using SESs. We evaluated the rate of procedural and clinical success, the incidence of in-hospital and long-term MACE, the recurrence rate of ISR after 6-8 months, and the risk factors for recurrent ISR and follow-up MACE.

RESULTS

Forty-five percent of the lesions were directly stented. After stent implantation, the minimal lumen diameter increased from 0.51 +/- 0.32 to 2.50 +/- 0.32 mm in the stents and to 2.30 +/- 0.35 mm in the lesions (acute gain 1.99 +/- 0.37 mm). The procedural success rate was 99%. The clinical success rate was 88%. MACE occurred in 2.0% of patients during hospitalisation and in 12.8% after a median follow-up of 15.1 months (interquartile range 8.4-19.7). The recurrence rate of ISR was 11.8% after a median follow-up of 7.7 months (interquartile range 7.4-8.4). The risk for recurrent ISR was significantly higher in patients with diabetes or hypertension, in those aged more than 65 years and in female patients, as well as in the lesions with a small minimal lumen diameter. Three-vessel disease and age were risk factors for MACE.

CONCLUSIONS

This study confirms the feasibility, safety and effectiveness of using SESs to treat ISR, and identifies a risk profile for recurrent ISR and MACE.

Comparison of six-month angiographic and three-year outcomes after sirolimus-eluting stent implantation versus brachytherapy for bare metal in-stent restenosis

To evaluate long-term effectiveness of sirolimus-eluting stent (SES) implantation for diffuse bare metal in-stent restenosis (ISR), we compared 6-month angiographic and long-term (3-year) clinical outcomes of SES implantation and intracoronary brachytherapy (ICBT). SES implantation for diffuse ISR was performed in 120 consecutive patients and their results were compared with those from 240 patients treated with beta-radiation with balloons filled with rhenium-188 and mercaptoacetyltriglycine. The radiation dose was 15 or 18 Gy at a depth of 1.0 mm into the vessel wall. The primary end point was 3-year major adverse cardiac events including myocardial infarction, cardiac death, and target lesion revascularization. The 2 groups were similar in baseline clinical and angiographic characteristics. Lesion lengths were 25.1 +/- 14.2 mm in the SES group and 24.5 +/- 10.4 mm in the ICBT group (p = 0.15). In-stent acute gain was greater in the SES group than in the ICBT group (2.23 +/- 0.62 vs 1.91 +/- 0.54 mm, p <0.001). We obtained 6-month angiographic follow-up in 287 patients (79.7%). In-segment angiographic restenoses were 7.4% (7 of 94) in the SES group and 26.4% (51 of 193) in the ICBT group (p <0.05). Two myocardial infarctions (1 in each group) and 5 deaths (4 in SES group, 1 in ICBT group) occurred during 3-year follow-up. At 3 years, survival rates without target lesion revascularization (94.1 +/- 2.2% vs 84.6 +/- 2.3%, p = 0.011) and major adverse cardiac events (92.5 +/- 2.4% vs 84.2 +/- 2.4%, respectively, p = 0.03) were higher in the SES than in the ICBT group. In conclusion, compared with ICBT, SES implantation for diffuse ISR is more effective in decreasing recurrent restenosis and improving long-term outcomes.

Four-year results after brachytherapy for diffuse coronary in-stent restenosis: will coronary radiation therapy survive?

BACKGROUND

Prior to the introduction of drug-eluting stents (DES), diffuse coronary in-stent restenosis (ISR) was mainly treated by brachytherapy (BT), with good short-term and mid-term results. However, there exist limited data on the long-term effects of BT that justify its continuous use.

MATERIALS AND METHODS

Two hundred patients with diffuse ISR treated with intravascular BT were retrospectively followed over 4 years. Group A (n=134) was treated with the noncentered (90)Sr/Y BetaCath radiation system, whereas Group B (n=66) was treated with the centered 32P Galileo source wire system. Primary endpoints after 4 years were target lesion restenosis (TLS) and target lesion revascularization (TLR). Secondary endpoints were target vessel revascularization (TVR) and nontarget vessel revascularization (NTVR), as well as major adverse cardiac events (MACE).

RESULTS

Follow-up at 4 years yielded a TLS rate of 37.6% (Group A, 40.8%; Group B, 31.1%; P=.48). TLR was performed in 34.8% of patients (37.5% in Group A vs. 29.5% in Group B; P=.55). Ten percent of patients underwent coronary bypass surgery. Percutaneous coronary intervention was performed more often in Group A (27.5%) than in Group B (19.7%), while TVR was less frequent in Group A (10.0%) than in Group B (18.0%). NTVR was undertaken in 25.0% of Group A patients versus 21.3% of Group B patients, and MACE occurred in 1.7% of Group A patients versus 3.3% of Group B patients. These differences were not statistically significant (P>.05).

CONCLUSIONS

While excellent short-term and mid-term results after coronary BT are widely accepted, a high TLS rate can be observed after 4 years. The potential superiority of DES to BT will depend on the availability of long-term clinical data.

Low-energy gamma-emitting stents inhibit intimal hyperplasia with minimal "edge effects" in a pig coronary artery model

PURPOSE

The objective of this study was to determine the effects of different doses of gamma-emitting radioactive stents on intimal hyperplasia in a porcine coronary stent model at 28 days.

METHODS

Sixty-four bare stents and those coated with palladium-103 [activities of 0 (control), 0.5, 1.0, 2.0, and 4.0 mCi] were implanted in the coronary arteries of 32 pigs. Stented segments were evaluated by histomorphometry at 28 days.

RESULTS

There was significantly more intima in the 0.5- and 1-mCi stents than in controls (4.27+/-0.52 and 4.71+/-1.13 vs. 1.71+/-0.61 mm(2); P<.0001). Neointimal formation in 2-mCi stents was similar to that in controls, while that in 4-mCi stents was reduced compared to that in controls (2.34+/-1.61 and 0.82+/-0.25 vs. 1.71+/-0.61 mm(2); P=NS and P<.05, respectively). Stent margin neointimal response was representative of that within the stent body, with nonsignficant modest increases in intimal area at adjacent nonstented segments in radioactive stent groups. There was a dose-dependent increase in inflammation scores. Radioactive stents had lower intimal smooth muscle and higher fibrin scores. There was an increase in adventitial fibrosis in 1- and 2-mCi stents versus controls (1.26+/-0.99, and 2.25+/-1.27 vs. 0.21+/-0.31; P<.001).

CONCLUSION

Dose-response inhibition of in-stent hyperplasia with minimal "edge effects" occurs with low-energy gamma-emitting stents. An increased inflammatory response at higher doses in palladium-103 stents indicates that later follow-up studies are necessary.

Implementing a best-treatment strategy with intracoronary brachytherapy for in-stent restenosis in patients at high risk for recurrence

BACKGROUND

The deployment of drug-eluting stents (DES) to treat bare-metal stent restenosis [in-stent restenosis (ISR)] has become routine practice, with a consequential decline in the use of intracoronary brachytherapy (ICBT). However, there are concerns as to the long-term safety profile of DES, particularly in terms of late stent thrombosis. In addition, an appropriate treatment strategy for stenosis within DES has not been developed. The aim of this study was to examine the efficacy of best treatment with ICBT for ISR in patients at high risk for future recurrence.

METHODS

Forty-seven consecutive patients with symptomatic ISR with at least one or more increased risk criteria for recurrence were treated with beta-radiation. The patients received best treatment based on avoidance of previously reported procedural risk factors for recurrence (incomplete stent apposition, dissection, geographical miss, and damage to the noninjured vessel segment), deferring ICBT when provisional stenting was performed. A beta-radiation dose of 20 Gy was used, and clopidogrel was prescribed for at least 6 months.

RESULTS

Treatment was successful for all patients without in-hospital complications. ICBT increased the total intervention procedure time by 15+/-10 min. ISR length was 25.4+/-11.5 mm. The angiographic minimal luminal diameter (MLD) was 2.24+/-0.43 mm after ICBT versus 0.75+/-0.58 mm at baseline (P<.05). On 9-month follow-up, the MLD was 1.93+/-0.48 mm (P<.05 vs. baseline). Binary restenosis was detected in six (13%) patients. At 29.7+/-9.3 months of follow-up, target lesion revascularization or target vessel (nonlesion) revascularization was performed in 17 (36%) patients. Only one patient suffered a myocardial infarction, and no deaths were observed.

CONCLUSION

The adoption of a best-practice protocol for the use of ICBT to treat ISR can result in a safe and effective clinical and angiographic outcome. Under these circumstances and with appropriate patient selection, ICBT may continue to be of value despite the popular use of DES.

Prevention of coronary restenosis with radiation therapy: a review

The problem of restenosis after percutaneous transluminal coronary angioplasty remains the major limiting factor of the procedure. Over the last 10 years, investigators have been studying the use of radiation therapy for preventing restenosis after angioplasty or stent placement. Since radiotherapy has been proven in other cases to be effective in disrupting the cell cycle regulatory proteins and thereby slowing or stopping growth, it was decided to apply the same principle to neointimal hyperplasia. To review the data that have emerged regarding vascular radiation with an emphasis on irradiated stents, 65 articles were reviewed and both preclinical and clinical experiments were included. Overall, studies with gamma and beta radiation show promising results. Endovascular gamma radiation has been shown effective in randomized trials, even at 3-year follow-up. Beta radiation is preferred because of greater safety and localization, and because it has also shown encouraging results in initial clinical trials, as well as in larger randomized studies. Consequently, the Federal Drug Administration has approved the use of both. In both types of endovascular brachytherapy, it seems the greater the dose, the better the initial response. Safety concerns include an increased incidence of late thrombosis and greater restenosis at margins. With irradiated stents, however, the situation is not as clear. At times, animal models have presented confusing results. These have ranged from significant suppression of hyperplasia to outright adverse effects of radiation on the vessel wall. While some clinical trials have been encouraging, others have not. Follow-up of up to 1 year has been disappointing so far. Many issues, such as the "candy wrapper" effect and rebound hyperplasia, must be dealt with before this becomes a viable form of therapy. It has become clear that radiation therapy in this setting, while having potentially great benefits, can cause deleterious effects as well. However, the mixed bag of positive and negative results seen so far, and the attractiveness of stents or percutaneous transluminal coronary angioplasty being "restenosis-proofed," eventually is cause for cautious optimism.

Two-Year Follow-Up of the Quantitative Angiographic and Volumetric Intravascular Ultrasound Analysis After Nonpolymeric Paclitaxel-Eluting Stent Implantation

OBJECTIVES

This study used serial angiographic and intravascular ultrasound (IVUS) analysis to evaluate the long-term efficacy of a nonpolymeric, paclitaxel-eluting stent coating on intimal hyperplasia (IH) 2 years after implantation.

BACKGROUND

Long-term efficacy of patients treated with nonpolymeric paclitaxel-eluting stents beyond 1 year has not been well determined.

METHODS

Patients were randomized to placebo or 1 of 2 doses of paclitaxel (low dose, 1.28 microg/mm2; high dose, 3.10 microg/mm2). Complete after-procedure, 6-month, and 2-year angiographic and IVUS data were available in 53 patients (17, 17, and 19 patients, respectively).

RESULTS

Baseline characteristics were similar among the 3 groups. Although 6-month minimal luminal diameter (MLD) was significantly smaller in placebo compared with paclitaxel-eluting stent patients (1.9 +/- 0.6 mm in placebo, 2.5 +/- 0.6 mm in low-dose, and 2.6 +/- 0.5 mm in high-dose patients, p = 0.004), the MLDs at 2 years were similar (2.3 +/- 0.6 mm, 2.3 +/- 0.7 mm, and 2.0 +/- 0.8 mm, respectively, p = 0.4). Despite a stepwise reduction in IH accumulation at 6 months (23 +/- 18 mm3 in placebo, 14 +/- 11 mm3 in low-dose, and 10 +/- 12 mm3 in high-dose, p = 0.017), the increase of IH volume from 6 months to 2 years was significantly greater in the high-dose patients (13 +/- 14 mm3 in high-dose vs. 4 +/- 7 mm3 in low-dose patients, p = 0.074; and vs. 1 +/- 13 mm3 in placebo, p = 0.019). Late target lesion revascularization (beyond 1 year) was performed in 2 high-dose patients.

CONCLUSIONS

Despite the suppression of IH after non-polymeric paclitaxel-eluting stents compared with bare-metal stents at 6 months, a "late catch-up" IH growth was found in the high-dose patients at 2-year follow-up.

Repeat intracoronary beta-brachytherapy using a rhenium-188-filled balloon catheter for recurrent restenosis in patients who failed intracoronary radiation therapy

BACKGROUND

Conventional percutaneous coronary intervention (PCI) in restenotic lesions after brachytherapy failure is associated with a high recurrence rate of restenoses and revascularizations. Intracoronary brachytherapy using a liquid rhenium-188-filled balloon in de novo or restenotic lesions safely and effectively reduced restenosis rates. We report clinical and angiographic data regarding the safety and efficacy of rhenium-188 brachytherapy in restenoses after brachytherapy failure.

METHODS

Fourteen patients with restenosis after brachytherapy failure received rhenium-188 beta-brachytherapy. Follow-up was performed angiographically after 6 months and clinically after 12 months. Primary clinical endpoint was the incidence of major adverse cardiac events (MACE) defined as any death, myocardial infarction or repeat revascularization in the target vessel within 12 months. Secondary angiographic endpoints were the binary restenosis rate and late loss in the total segment including edge effects at 6 months.

RESULTS

The prescribed dose of 22.5 Gy (n=12) or 30 Gy (n=2) was successfully delivered in all patients. In two lesions, a bare-metal stent was implanted. The mean length of the irradiated segment was 40.0+/-15.7 mm. The mean diameter of the irradiation balloon was 2.96+/-0.37 mm. Angiographic follow-up was done in 13 of 14 patients. There was no edge stenosis or coronary aneurysm. Within the total segment, late loss was 0.39+/-0.64 mm and late loss index was 0.18+/-0.40 with a binary restenosis rate of 23%. Twelve months' clinical follow-up was available in all patients, which showed a MACE rate of 7% due to one target lesion revascularization (TLR).

CONCLUSIONS

Intracoronary beta-brachytherapy with a liquid rhenium-188-filled balloon in restenoses after intracoronary radiation therapy failure including 12 months combined antiplatelet therapy is safe with respect to vessel thrombosis, late coronary occlusion or aneurysm formation. With limited use of stenting, angiographic and clinical follow-up for repeat brachytherapy were favorable and it is associated with low restenosis and target vessel revascularization rate.

Clinical outcome of patients undergoing low aggressive angioplasty combined with brachytherapy and short-term dual antiplatelet therapy for in-stent restenosis

OBJECTIVE

The impact of vessel injury on the outcome of patients undergoing percutaneous coronary intervention combined with brachytherapy for in-stent restenosis is under investigation. We report our clinical experience adopting a low aggressive balloon angioplasty technique, to limit vessel trauma, associated with brachytherapy and short-term dual antiplatelet therapy.

METHODS

Forty-nine consecutive patients, undergoing percutaneous coronary intervention with brachytherapy for symptomatic in-stent restenosis, were prospectively observed for a median time of 21 + or - 8 months. Clinical follow-up included anginal status, death, myocardial infarction and repeat revascularization; only patients with evidence of ischaemia repeated coronary angiography. Low aggressive angioplasty consisted in the use of a conventional balloon with a balloon to artery ratio < or = 1, avoiding high inflation pressures and the use of other devices. Dual antiplatelet therapy was continued for 3-6 months.

RESULTS

Early angiographic result was good and the need for additional stent implantation was low (3.9%). At follow-up, we did not observe death, acute myocardial infarction or stent thrombosis, but 10 patients repeated coronary angiography for recurrence of ischaemia: disease progression was present in two cases (4.1%). Restenosis emerged in the remaining eight patients (16.3%): two cases showed restenosis within the target lesion segment, one case within the injured segment, one case within the radiated segment, and four cases at the edges. The consequent new revascularization was surgical in three patients and percutaneous in seven patients.

CONCLUSIONS

Our data suggest that low aggressive angioplasty followed by brachytherapy and short-term dual antiplatelet therapy for in-stent restenosis is related to a good outcome, with a low restenosis rate and without stent thrombosis.

Endovascular Brachytherapy for Prophylaxis of Restenosis after Femoropopliteal Angioplasty: Five-year Follow-up—Prospective Randomized Study

PURPOSE

To report the 5-year results from the prospective randomized Vienna-2 trial, which was designed to evaluate the safety and effectiveness of adjunctive endovascular brachytherapy (EBT) compared with no further treatment after successful revascularization in patients with long-segment femoropopliteal lesions.

MATERIALS AND METHODS

Each patient gave written informed consent to participate in the study, which was approved by the hospital's ethics committee. One hundred two patients (men, 53.9%; mean age, 72.1 years +/- 8.7 [standard deviation]; lesion length, 8.1 cm +/- 4.9) underwent percutaneous transluminal angioplasty (PTA) without further stent implantation. Patients were then assigned to either receive EBT (n = 51) by using an iridium 192 source, with a prescribed dose of 12 Gy at 3 mm from the source axis, or no further treatment (n = 51). Radiation was delivered without a centering catheter. Data were analyzed by using a Student t test for continuous values and a chi(2) test to compare categorical values. A Cox proportional hazards regression analysis was performed to evaluate predictors of recurrence at follow-up.

RESULTS

After 6 months, the restenosis rate for the 102 patients with completed 5-year follow-up was significantly reduced for the PTA plus EBT group versus the PTA alone group (29.4% vs 56.9%, P < .05). During follow-up we observed a late catch-up phenomenon, and after 5 years the recurrence rate was comparable in both groups (72.5% vs 72.5%, P > .99). Time to recurrence, however, was significantly delayed in the PTA plus EBT group (17.5 months +/- 14.7 vs 7.4 months +/- 6.8 for the PTA alone group, P < .05).

CONCLUSION

At 5-year follow-up, PTA followed by gamma radiation EBT with a dose of 12 Gy resulted in a delay but not an inhibition of restenosis when compared with that of PTA alone.

The role of radiation therapy in benign diseases

Although adequate prospective data are lacking, radiation therapy seems to be effective for many benign diseases and remains one of the treatment modalities in the armamentarium of medical professionals. Just as medication has potential adverse effects, and surgery has attendant morbidity, irradiation sometimes can be associated with acute and chronic sequelae. In selecting the mode of treatment, most radiation oncologists consider the particular problem to be addressed and the goal of therapy in the individual patient. It is the careful and judicial use of any therapy that identifies the professional. With an understanding of the current clinical data, treatment techniques, cost, and potential detriment, the goal is to provide long-term control of the disease while minimizing unnecessary treatment and potential risks of side effects. The art lies in balancing benefits against risks.

Intracoronary β-brachytherapy using a rhenium-188 filled balloon catheter in restenotic lesions of native coronary arteries and venous bypass grafts

PURPOSE

We have previously demonstrated the efficacy of intracoronary beta-brachytherapy using a liquid (188)Re-filled balloon in a randomised trial including de novo lesions. Percutaneous coronary interventions in restenotic lesions and in stenoses of venous bypass grafts are characterised by a high recurrence rate for restenosis and re-interventions. Against this background, we wanted to assess the impact of intracoronary beta-brachytherapy using a liquid (188)Re-filled balloon in restenotic lesions in native coronary arteries and venous bypass grafts.

METHODS

In 243 patients, beta-brachytherapy with 22.5 Gy was applied at a tissue depth of 0.5 mm. Patients were followed up angiographically after 6 months and clinically for 12 months. The primary clinical endpoint was the incidence of MACE (death, myocardial infarction, target vessel revascularisation). Secondary angiographic endpoints were late loss and binary restenosis rate in the total segment.

RESULTS

All irradiation procedures were successfully performed. A total of 222 lesions were in native coronary arteries; 21 were bypass lesions. Mean irradiation length was 41.6+/-17.3 mm (range 20-150 mm) in native coronary arteries and 48.1+/-33.9 mm (range 30-180 mm) in bypass lesions; the reference diameter was 2.57+/-0.52 mm and 2.83+/-0.76 mm, respectively. There was no vessel thrombosis during antiplatelet therapy. Angiographic/clinical follow-up rate was 84%/100%. MACE rate was 17.6% in the native coronary artery group and 38.1% in the CABG group (p<0.03). Binary restenosis rate was 22.5% and 55.6% (p<0.01), and late loss was 0.38+/-0.72 mm and 1.33+/-1.11 mm (p<0.001), respectively.

CONCLUSIONS

We conclude that intracoronary beta-brachytherapy with a liquid (188)Re-filled balloon using 22.5 Gy at a tissue depth of 0.5 mm in restenotic lesions is safe. It is associated with a low binary restenosis rate, resulting in a low occurrence rate of MACE within 12 months in restenotic lesions in native coronary arteries but not in vein grafts.

Intracoronary radiotherapy with a 188Rhenium liquid-filled angioplasty balloon system in in-stent restenosis: a single-center, prospective, randomized, placebo-controlled, double-blind evaluation

BACKGROUND

In cases of in-stent restenosis, intracoronary radiotherapy with beta-emitters and gamma-emitters has been shown to reduce the risk of repeat restenosis. The present randomised, placebo-controlled study addresses the question of whether intracoronary radiotherapy applied by the easy-to-handle Rhenium liquid-filled angioplasty balloon system is also able to reduce the angiographic re-restenosis rate in stents.

METHODS AND RESULTS

At our center, from May 2000 to December 2003, 165 patients (mean age 64+/-10, median 65 years; 127 men, 38 women) with symptomatic in-stent restenosis underwent either intracoronary brachytherapy or sham procedure. Index clinical and angiographic parameters were largely comparable in both groups. Radiation therapy was performed with a standard percutaneous transluminal coronary angioplasty (PTCA) balloon catheter inflated with liquid Rhenium in the redilated in-stent restenosis for 240-890, mean 384+/-125 s with low pressure (3 atm) in order to reach 30 Gy at 0.5 mm depth of the vessel wall. In 82 patients, intracoronary radiotherapy was carried out without complications, but one of the 83 patients who underwent sham procedure suffered small myocardial infarction. During follow-up, stent thrombosis with subsequent non-Q-wave myocardial infarction occurred in one patient in each group (6 days and 8 months after the procedure, respectively). At 6 months after the index procedure, repeat angiography was performed in 156 of the 164 patients with successful procedure (rate 95%): restenosis (stenosis >50% in diameter) or reocclusion was observed in only 19 of 78 (=24%) patients of the radiation but in 31 of 78 (=40%) patients of the sham procedure group (P=0.04). Event-free survival (free of death, myocardial infarction, target vessel revascularization) at 1 year was 87% for patients being radiated and 74% for patients having undergone sham procedure (P=0.05).

CONCLUSIONS

Intracoronary radiation therapy with the liquid-filled beta-emitting Rhenium balloon is not only easy to perform, safe, and comparably inexpensive but also an effective option to prevent repeat restenosis and the need for target vessel revascularization in cases of in-stent restenosis.

Ionizing radiation to prevent arterial intimal hyperplasia at the edges of the stent: induces necrosis and fibrosis

BACKGROUND

Although ionizing radiation has been proposed for the prevention of intimal hyperplasia in coronary and peripheral arteries in multicenter clinical trials, information is lacking on how irradiation affects arterial histology after stenting and especially how it affects the edges of the stent. We investigated intimal hyperplasia recasting with histological changes in arterial wall at the edges of the stent after arterial stenting followed by adequate external radiation for the prevention of intimal hyperplasia in pigs.

MATERIALS AND METHODS

The aorta was experimentally stented in 30 pigs who were then assigned to two groups: irradiation with 20 Gy and a control group with no irradiation. The aorta was resected for morphometric and histological studies 6 weeks after procedure.

RESULTS

Intimal thickness was reduced and the intima/media ratio was significantly lower in irradiated groups than in control pigs. In the irradiated group histological examination at the edges of the stent showed thin neointimal proliferation with an intact endothelium. In all sections analyzed in the 20-Gy irradiated group the vascular media at 45 days contained necrotic areas and fibrosis with calcifications.

CONCLUSIONS

After arterial injury, adequate ionizing radiation effectively reduces neointimal thickening. Irradiation-induced histological changes include previously undetected recasting with necrosis and fibrosis at the arterial edges of the stent. The parietal recasting we observed in animal arteries irradiated at high doses is unclear and a cause of concern especially after clinical spontaneous dissection was recently reported. The use of ionizing radiation for the prevention of arterial restenosis awaits confirmation with a long-term follow-up including specific experimental histological analyses.

Incomplete Neointimal Coverage of Sirolimus-Eluting Stents

OBJECTIVES

The goal of this study was to use angioscopy to investigate the amount of neointimal coverage after sirolimus-eluting stent (SES) implantation.

BACKGROUND

Sirolimus-eluting stents reduce intimal hyperplasia.

METHODS

We used angioscopy to evaluate 37 consecutive stented coronary artery lesions (15 SES and 22 bare-metal stents [BMS]) in 25 patients (18 men, 7 women) at 3 to 6 months after stent implantation. Angioscopic evaluation focused on: 1) neointimal coverage of stent struts, and 2) the existence of thrombi. The degree of neointimal coverage was classified as grade 0 when there was no neointimal coverage (similar to immediately after the implantation); grade 1 when stent struts bulged into the lumen, but were covered and still translucently visible; grade 2 when stent struts were visible but not clearly seen (not translucent); and grade 3 when stent struts were not visible because they were embedded in the neointima.

RESULTS

Thrombi were identified in eight stented segments, tended to be more common with SES (p = 0.14), but were not seen on angiography. Three of the 15 SES (20%) had grade 0 neointimal coverage, and only 2 SES (13.3%) had complete coverage (grades 2/3). In contrast, all 22 BMS showed complete intimal coverage (grades 2/3). Thrombi were more common in stents with incomplete neointimal coverage (p = 0.09).

CONCLUSIONS

The SES had incomplete neointimal coverage three to six months after implantation, and this was associated with subclinical thrombus formation.